1. Field of the Invention
The invention concerns a device for producing a glass rod according to the so-called Danner process, particularly for producing a glass tube. Devices of the named type are known from a plurality of publications. Reference is made to DE 199 60,211 A1 only by way of example.
2. Description of Related Art
Such a device comprises a pipe, the so-called Danner blowpipe, which rotates slowly and which is generally found inside a heating muffle. Generally the Danner blowpipe is conical and is inclined by its longitudinal axis slightly toward the horizontal plane. On one end of the blowpipe—the larger end in the case of conical blowpipes—a continuous stream of molten glass is introduced, which forms a laminar trickling film on the jacket surface of the blowpipe. At the smaller end of the blowpipe, the glass rod is drawn off, either as a solid rod or as a tube. After reversing direction in the horizontal plane, the solidifying rod passes through a roller conveyor up to a drawing machine connected downstream. It is then broken down into segments of specific length.
The glass stream has a temperature of approximately 1300° C. when it arrives on the supply end of the Danner blowpipe and a temperature of approximately 1000° C. at the so-called a “drawing bulb”. A cooling process thus takes place from the supply end to the discharge end. The cooling process proceeds by the introduction of heat from the heating muffle in controlled manner.
DE 198 03,327 C2 refers to a tube-pulling plant according to Danner for glass tubes. The plant comprises a carrier component of ceramics with metal coating.
DE 2,112,692 A1 describes a leading body for the production of tubes or rods of glass. Here, a hollow body is supported on a spindle. It is rigidly joined with the spindle on one end and is joined in a spring-displaceable manner on the other end.